The Spanish government, through the state's legal service, has told the government of Valencia, headed by Ximo Puig (PSOE), it should communicate with its counterparts in Catalonia and the Balearic Islands in Spanish. The government's lawyers base this claim on the fact that the Valencia's Statute of Autonomy declares Valencian to be a co-official language in the autonomous community, whilst the Statutes of Catalonia and the Balearic Islands put Catalan in this position.
Whether Catalan and Valencian should be considered separate languages or dialects of the same one is a contentious issue; Ethnologue, a standard reference in the field of linguistics, considers them to be the same language, and they share the same ISO 639 code. In any case, they have a very high degree of mutual intelligibility that neither shares with Castilian Spanish.
As first reported by the newspaper Ara, that's one of the conclusions of an opinion filed with the Supreme Court in Madrid. The court's third chamber is hearing an appeal from the Valencian government and a Valencian union against a ruling by the High Court of Justice of Valencia which struck down parts of a decree establishing Valencian as the preferred language in the public administration.
The lawyers say the law only allows communications between two autonomous communities to not be translated into Castilian Spanish if they share a co-official language. This condition is not met in this case, they argue, as the communities' Statutes of Autonomy use different terms.
They note that the Constitutional Court, in 1997, found them to be essentially equivalent, but argue that this, being in a case involving the University of Valencia, has no relevance beyond the world of academia and that this case needs to be resolved purely on the basis of the law.
They also support the original verdict by the High Court of Justice of Valencia, saying that making Valencian a preferred language counts as discrimination against Spanish.